【作者】 袁健；

【导师】 杨伟；

【作者基本信息】 南京理工大学 ， 电力系统及其自动化， 2019， 硕士

【摘要】 随着分布式电源在电网中的渗透率越来越高,直流输电工程的开展,电力电子变压器的广泛应用,越来越多的变流器应用于电网,电力系统电力电子化程度越来越高。由于电力电子器件快速响应的内禀性,电力系统出现了惯量缺乏和阻尼下降等问题,导致其安全裕度减小。虚拟同步发电机控制技术能使变流器模拟同步发电机的机电暂态特性,具有转动惯量、阻尼特性、调频调压特性以及并离网通用的技术优势。在传统机组占主导地位的电力系统中,众变流器在长时间内仍需追踪“同步”电网,研究虚拟同步发电机技术具有重要现实意义。因此,论文对微电网中逆变器在不同运行工况下虚拟同步发电机的控制策略进行了研究。论文首先概述了同步发电机的基本原理与优缺点,在此基础上给出了虚拟同步发电机的控制结构与实现原理,为增强谐波抑制效果并加快动态响应速度,利用二阶广义积分器与三阶广义积分器级联,提出了相应的虚拟阻抗设计方法。其次,针对多机并联系统中无功功率分配不均的问题,提出了基于电压补偿的无功控制方法;为解决直流分量引起的功率振荡问题,给出了基于准谐振控制器的底层双环控制方法;为了保证虚拟同步发电机在双模式下能够平滑无缝切换,给出了预同步控制策略;为了提高虚拟同步发电机非对称运行能力,分别提出了不平衡负载下和不平衡电网电压下的均衡控制策略;为了解决光储虚拟同步发电机运行时需要兼顾光伏阵列最大功率追踪控制与储能装置充放电控制,给出了基于虚拟同步发电机的光储系统协调控制策略。最后基于Matlab/Simulink平台,对上述控制方法进行了仿真分析,结果验证了所提策略的正确性和有效性。更多还原

【Abstract】 With the increasing penetration of distributed generation in power grid,the development of HVDC and the extensive application of power electronic transformer,more and more converters are used in power grid,and the degree of power electronization in power system is getting higher and higher.Due to the intrinsic characteristics of power electronic devices,the lack of inertia and the decrease of damping in power system lead to the decrease of security margin.Virtual synchronous generator(VSG)can make the converter simulate the electromechanical transient characteristics of synchronous generator,and has unique technical advantage,such as virtual inertia,virtual damper,frequency and voltage regulation,seamless switching between grid-connected and islanding mode.In the traditional power system dominated by generator sets,the mass converters still need to track the power grid for a long time,so it is of great practical significance to study the virtual synchronous generator.Therefore,the control strategy of virtual synchronous generator in microgrid under different operation conditions is studied in this paper.Firstly,the basic principle of synchronous generator are summarized.On this basis,the control structure and realization principle of virtual synchronous generator are given.In order to enhance the effect of harmonic suppression and speed up the dynamic response,a virtual impedance design method is proposed by cascading a second-order generalized integrator with a third-order generalized integrator.Secondly,aiming at the unreasonable sharing of reactive power in multi-machine parallel system,a reactive power control method based on voltage compensation is proposed.In order to solve the problem of power oscillation caused by DC component,a double-loop control method based on quasi-resonant controller is presented.In order to ensure seamless switching between grid-connected and islanding mode,a presynchronization control strategy is presented.In order to improve the asymmetric operation capability of virtual synchronous generator,balanced control strategies under unbalanced load and unbalanced grid voltage are proposed respectively.In order to combine PV generation and storage energy compensation,a coordinated control strategy is established.Finally,based on the platform of MATLAB/Simulink,the above control methods are simulated and analyzed,and the results verify the correctness and effectiveness of the proposed strategy.更多还原